Anodal Transcranial Direct Current Stimulation Does Not Facilitate Dynamic Balance Task Learning in Healthy Old Adults

Abstract

Older adults frequently experience a decrease in balance control that leads to increased numbers of falls, injuries and hospitalization. Therefore, evaluating older adults’ ability to maintain balance and examining new approaches to counteract age-related decline in balance control is of great importance for fall prevention and healthy aging. Non-invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) have been shown to beneficially influence motor behavior and motor learning. In the present study, we investigated the influence of tDCS applied over the leg area of the primary motor cortex (M1) on balance task learning of healthy elderly in a dynamic balance task (DBT). In total, 30 older adults were enrolled in a cross-sectional, randomized design including two consecutive DBT training sessions. Only during the first DBT session, either 20 min of anodal tDCS (a-tDCS) or sham tDCS (s-tDCS) were applied and learning improvement was compared between the two groups. Our data showed that both groups successfully learned to perform the DBT on both training sessions. Interestingly, between-group analyses revealed no difference between the a-tDCS and the s-tDCS group regarding their level of task learning. These results indicate that the concurrent application of tDCS over M1 leg area did not elicit DBT learning enhancement in our study cohort. However, a regression analysis revealed that DBT performance can be predicted by the kinematic profile of the movement, a finding that may provide new insights for individualized approaches of treating balance and gait disorders.

Comparison of Transcranial Direct Current Stimulation of the Primary Motor Cortex and Cerebellum on Static Balance in Older Adults

“…In contrast, Kaminski et al (28) showed that M1 tDCS did not affect balance learning in the elderly. Differences in the findings can be related to differences in the type of outcome, which was dynamic balance in the study by Kaminski et al (28) and static balance in the current study. In another study, Zhou et al (42) reported that a-tDCS could not change the duration of Timed Up and Go (TUG) test in older adults.…”

“…a-tDCS of the cerebellum had no significant effects on balance (25)(26)(27). These controversial findings show that age is a factor, which may affect the outcomes of brain stimulation techniques (7,28,29).…”

“…M1 tDCS may increase the excitability of leg muscles in patients with stroke (39), toe pinch force in lower extremities (40), and knee extension performance in bodybuilders (41). In contrast, Kaminski et al (28) showed that M1 tDCS did not affect balance learning in the elderly. Differences in the findings can be related to differences in the type of outcome, which was dynamic balance in the study by Kaminski et al (28) and static balance in the current study.…”

The Effects of Transcranial Direct Current Stimulation (tDCS) on Balance Control in Older Adults: A Systematic Review and Meta-Analysis

“…After completing the full-text review, one conference abstract and one study without providing study protocol were excluded. Ten studies examining the effects of tDCS on balance and mobility in older adults with relatively healthy status or with functional impairment (e.g., stroke, slow gait) (Kaski et al, 2013;Manor et al, 2015Manor et al, , 2018Saeys et al, 2015;Zhou et al, 2015Zhou et al, , 2018Ehsani et al, 2017;Kaminski et al, 2017;Nomura and Kirimoto, 2018;Yosephi et al, 2018) were accepted to be included in the systematic review and meta-analysis. Figure 2 illustrates the results of the Cochrane risk of bias tool.…”

“…Seven of the studies used sponge electrodes of the same size (i.e., 35cm 2 ) (Manor et al, 2015(Manor et al, , 2018Saeys et al, 2015;Zhou et al, 2015Zhou et al, , 2018Ehsani et al, 2017;Yosephi et al, 2018), while other three studies used electrodes of different sizes (Kaski et al, 2013;Kaminski et al, 2017;Nomura and Kirimoto, 2018). Kaminski et al (2017) for example, used smaller-size anodes and larger-size cathodes. The target current intensity of tDCS used in these studies was set as 1, 1.5 or 2 mA ( Table 2).…”